4 October 1957 the Soviet Union launched “Sputnik 1” which rose above the earth’s atmosphere and went into orbit of our planet, making a complete revolution around it in 90 minutes. In conditions of clear sky peace of those times, it was the only kind of object: artificial, man-made satellite. Unofficially, this meant the beginning of the space race, military and political activities which for decades was fascinated by international politics.
But “Satellite” in Earth orbit has not. In fact, he stayed there so long that by the time of the launch of Explorer 1, first U.S. satellite in space, around the Earth for quite some time flying the “Sputnik 2” with the first animal in space. But the original Sputnik, completing 1400 orbits, fell to the Ground.
What happened to the “Companion” was quite expected. In fact, this happens with most satellites, if you launch them into orbit and give to themselves. With each completed orbit, the first satellite reaches the apogee, the maximum distance from the Earth’s surface, and then the perigee, the closest it approaches Earth. For low earth orbit it essentially means that the satellites are within a few hundred kilometers above the Earth’s surface. Given that the line separating the Earth’s atmosphere and outer space, is at an altitude of only 100 kilometers, at first glance it may seem that the satellites must permanently remain in space.
But in reality, the situation is much more complicated. The atmosphere is not a sudden end or border. Gaseous state does not tend to take the form for some reason except the following: as you climb higher, the particle density will continue to fall, but different particleswhich are heated by collisions, will move with different speed: some faster, some slower, but with a clearly defined average speed.
The higher you go, the more likely you will find particles that have more energy, because to rise to great heights need more power. The density of such particles at high altitude will, of course, lower, but never drops to zero.
We found the atoms and molecules that remain gravitationally bound to the Earth at altitudes of up to 10,000 kilometers. The only reason we did not go beyond 10,000 miles, that at this altitude the Earth’s atmosphere becomes indistinguishable from the solar wind: both consist of hot atoms and ionized particles.
The vast majority of our atmosphere (by mass) is contained in the lowest layers in the troposphere account for 75% on the stratosphere for another 20% in the mesosphere — almost 5%. But the next layer, the thermosphere, is incredibly scattered.
While atmospheric particle at sea level must travel a microscopic distance to collide with another molecule, the thermosphere is so diffuse that an ordinary atom or molecule can overcome the kilometer and with nothing to face.
The thermosphere may seem like empty space, because even the atom can not be found. But rising to the height of the Earth’s atmosphere, you linger in the back of this abyss of low density, being at your peak parabolic orbit, and then slowly return to their home planet under the action of gravity.
But if you spacecraft, you will experience something completely different. The reasons are as follows:
- You do not rise from the Ground and wrap around her in an orbit, that is, move in the opposite direction to the hot air particles.
- Since you are in a stable orbit, you have to move fast: at least 7 miles per second to stay in space.
- You have dimensions not of the atom but of the spacecraft.
- These three points together lead to disaster for any satellite in orbit.
Such a disaster is inevitable because of the resistance faced by the satellite, which determines how much the speed of the satellite loses over time due to atmospheric particles that enter it at a relatively high speed. Any satellite in low earth orbit will have a lifespan from several months to several decades, but no more. You can fight it, climbing higher, but it won’t help much.
Whenever the Sun erupts with some activity, like sunspots, solar flares, coronal mass ejections or other explosive events, the Earth’s atmosphere heats up. The hotter the particles, the higher the speed, higher speeds will mean that they rise above, increasing the density of the atmosphere, even in space. When this happens, even companions, which were almost beyond the gravitational attraction, begin to fall to the Ground. Magnetic storms can also increase the density of the air at extremely high latitudes.
And this process is cumulative, in the sense that since the satellite is experiencing attraction, its perigee drops to lower and lower altitudes. Now, at these lower altitudes, the drag force increases even more, and this leads to the fact that you lose your kinetic energy, which keeps you in orbit even faster. The final death spiral it may take thousands, tens of thousands or even hundreds of thousands of orbits, but because the orbit is completed in 90 minutes, any satellite in low earth orbit will live a few decades at best.
This problem of falling back to Earth was not only a problem for the first satellites of the 1950s years, but remained a problem for almost all satellites that we have ever launched. 95% of all created by people satellites are in earth orbit, including the International space station and the Hubble space telescope. If we periodically clocked these devices, many of them already fell to the Ground.
From the Hubble and the ISS would be less than 10 years in their current orbits, if we just let them die. And while the great companions and die, they do so at the expense of uncontrolled entry into the atmosphere. Ideally, they should burn up in the atmosphere or fall into the ocean, but if the debris will fall on the people, would be a disaster.
And a telescope “Hubble”, too, must fall to the Ground. Its orbit will decrease. The telescope will be fine, but with each orbit it will be closer and closer to the Ground.
The final mission of the telescope includes the docking mechanism, which was installed on the telescope: Soft Capture and Rendezvous System. Any fitted properly will be able to safely deliver the telescope home.
But if you talk about 25 000 other satellites in low earth orbit, to carry out a controlled reentry is not possible. The Earth’s atmosphere will drop them below the line of the Pocket, below the space that we drew. If you stop launching satellites today, a hundred years will not have any traces of presence of mankind on earth orbit.
“Sputnik-1” was launched in 1957 and just three months later he spontaneously descended from orbit and fell to the Ground. Particles in our atmosphere rises much higher than any of the artificial lines that we’ve drawn, affecting all our satellites. The farther away the perigee, the longer you’ll stay in orbit. Until we have technology that will maintain the satellites in orbit without fuel, the Earth’s atmosphere will remain the most destructive force in preventing human presence in space.
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